Betta Fish: Is this finrot or just curly tail?

This betta, Zumo, has been living with me for 10 days now

During the first 3 days, I was waiting for his tank to settle down nicely before I put him in it, so he was living in a small bowl. Then, I noticed that he wasn't very active. Some part of his fin appeared curly & little ragged. His tail also kept sanking when he paused mid swim

I thought it was a stress-induced finrot, so I made the decision to transfer him to his current 5 gallon tank, and do fish in cycle.

Now he is very active, but his fin still remains quite rough. So I wonder if it's finrot or just his gene.

Here is our current routine

• the tank got 50% water change daily + 10drop of prime treatment
• Zumo got a 1 hrs medicine bath daily. The bath include 1 sea salt pallet, 2 drop of Suma's red cap formula, 2 drop of Suma's green drop formula